Immature Mountain Beaver

Immature Mountain Beaver

California is a hot spot for rare, threatened, and endangered species (RTEs). California has the largest number of rare plants and animals of any state in the nation and our region of the state, Humboldt County, is no exception. Many of these species are at risk and are declining, while others remain stable or are increasing.

Not surprisingly, while on a routine site visit near the coast, I bumped into the dwelling place of a local rare species: the Humboldt Mountain Beaver.

The Humboldt Mountain Beaver (Aplodontia rufa humboldtiana) is a local endemic subspecies of the Mountain Beaver that is native to the Humboldt/Del Norte counties region. As with many species, the name is about as inaccurate as can be. This subspecies is found close to the coast, and is not a beaver at all, but rather a large rodent, typically growing to a length of 12 inches (30.5 cm). This subspecies is generally found on north facing slopes near ample water sources, with dense cover, on steep hillsides with loose soil. The mountain beavers have such specific habitat requirements due their unique life history. North facing slopes and coastal settings generally have lower temperatures, protecting individuals from high temperatures which can be lethal. Simplified kidney function requires ample water within easy reach. Dense herbaceous cover is needed for protection from predators, as well as for forage material, while steep loose hillsides allow for burrow creation. These requirements restrict its range and the habitat area it may inhabit to very specific locations. Many of the sites where the Humboldt Mountain Beaver may live are being impacted by human development, as was the case where I observed the Humboldt Mountain Beaver burrows.

Humboldt Mountain Beaver Habitat

Humboldt Mountain Beaver Habitat

This encounter required an innovative solution that would allow continued use of the area to meet the needs of the landowner, while ensuring the continued persistence of the Humboldt Mountain Beaver. With the site visit over, back in the comfort of the Streamline Planning office in Arcata, we crafted an ESHA (Environmentally Sensitive Habitat Area) that would protect the location of the Burrows as well as the foraging range of the Humboldt Mountain Beaver, while permitting continued improvement and maintenance of the landowners driveway in a manner that did not increase costs, or jeopardize the health of this unique species. In addition to the new ESHA boundary, the landowner agreed to the purchase and planting of additional native forage herbs and tree species for shading of the habitat area to improve the habitat value for the Humboldt Mountain Beaver at this site. While I realize that there are times when the outcome to such a conflict does not end in such a rosy way, it is encouraging to note that there are ways to protect rare species while allowing for continued use and improvement of property to meet the needs of our local community, which is essential for the continued persistence and health of our local RTE’s and the health of our local community.

About Joseph Saler

Joseph is our botanist completing rare plant surveys, botanical as well as biological surveys, wetland delineations and ecological monitoring. Joseph’s background in local flora and experience in keying unknown species allow him to make accurate and thorough vegetation studies. He has completed vegetation surveys on large timber harvest plans and has experience in invasive species removal. Joseph has spent many years doing ecological restoration, guest education and landscaping at a resort ranch in the Bay Area, as well as pursuing permaculture practices at his family home in Calistoga and in the landscaping business in Humboldt county.

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